Method of casting cylinder heads



y 1930. 'r. PICKERING 1,769,456

METHOD OF CASTING CYLINDER HEADS Filed Aug. 28, 1929 2 Sheet-s-Shet 1 CJ 1 rm 1' inmiiiiii a) 1 1 1 rr "iiillii'iii- 51 1 J rr iiliilllim!INVENTOR ATTORNEY July 1, 1930.

'r. PICKERING 1,769,456

METHOD CASTING CYLINDER HEADS Filed Aug. 28, 1929 2 Sheets-Sheet 2 9ATTORNEY Patented July 1, 1930 PATENT OFFICE mnonoml ncnnme, OI BATAVIA,NEW YORK, ASSIGHOB 'I'O DOEHLEB DIR-CASTING (XL, A CORPORATION 01 NEWYORK m0!) 0] CASTING HEADS Application fled August In, 1989. 561181 I0.888,804.

My invention relates to a method of casting cylinder heads for internalcombustion engines. In particular, the mvention contem lates a methodwhereby permanent mollds are used in casting cylinder heads for aircooled internal combustion engines.

Owin to the irregular contour of a cylinder hea for an air cooledinternal combustion engine, the formation of a suitable mold in which tocast the cylinder head presents numerous difliculties. The cylinder headhas a clearance cavit in its bottom, the sides of which are un ercut inone transverse axis. Elbow inlet and outlet passages communicate withthe clearance cavity and lateral sparlilplug open are rovided inopposite w s of t e cy nder head and open into the clearance cavity. Theouter surface of the side wall of the cylinder head is provided withcircumferentiahheat radiating or cooling fins and the top wall has aplurality of parallel heat radiatin fins disposed transversely to theinlet an outlet passages.

Heretofore, such cylinder heads have been cast in sand molds in theusual manner, that is, by forming a sand mold for each castin andpouring the metal into the mol These sand molds which are re roduced foreach casting require considerab 0 care in the making as the rotrudingportions which form the heat radiating fins are delicate and easilybroken and distorted. Castings produced in such molds are, in general,rough and uneven and require considerable machining to remove theroughness therefrom.

In accordance with my invention, I am enabled to produce a cylinder headfor air cooled internal combustion engines which is smooth and accurateand requires no subsequent machining operations. I utilize a method forcasting cylinder heads in which permanent molds are employed.

My method enables me to employ a permanent collapsible core for formingthe undercut clearance cavity in the bottom of the cylinder head.

Other features and advantages of the invention hereinafter moreparticularly appear, and the invention will be pointed out in claims.

In practicing my invention, I em 10y a bedplate upon which the castingis adapted to Frest, and a two-part permanent mold which is separable ona plane that is normal to the fins extending from the to of the cylinderhead. A three-part co lapsible core, which is complemental in shape tothe clearance cavity, 1s inserted in and supported by the mold.Disintegratable cores complementary in shape to the inlet and outletassages are supported at one end by the be late and with their otherends contact wit the clearance cavity core. Lateral spark plug cores andlongitudinal valve stem cores are also inserted in and supported by themold, the spark plug cores contacting with the clearance cavit core andthe valve rod cores contacting with the cores of the inlet and outletassages. Into the assembled mold, the met consistin of an alloy ofaluminum, is poured. he threeart core is then collapsed and remove andthe spark lug and valve rod cores are removed. he mold is then openedand the casting lifted from the bedplate, and the cores in the elbowpassages are disinte ated and removed.

The met od will be further explained in connection with the constructionof mold illustrated in the drawings in which:

Fig. 1 is a side elevation of a cylinder head cast in accordance with myinvention;

Fig. 2 is a longitudinal section of the same;

Fig. 3 is a transverse sectional elevation of a mold, showing the partsof the mold separated after a cylinder head has been cast; and

Fi 4 is a lon 'tudinal sectional elevation of t e same ta en on the line44 of Figure 3.

In the drawings, there is represented a cylinder head for an air cooledinternal combustion engine, the casting of which head will serve toillustrate the invention. The cylinder head is composed of an alloy ofaluminum and is adapted to rest on the head end of the cylinder, thebottom 1 being secured in sealing contact with the edge of the cylinder.A clearance cavity 2 is provided in the bottom, the sides 3 of which areundercut in one transverse axis as at 4. Aligned and oppositely o eninginlet and outlet passages 5 and 6 o elbow she and opposed lateral arkplu openin in the walls 3 commumcate wit the c earance cavit 2. Theouter surface of the side wall 3 o the cylinder head is rovided with aplurality of circumferentiiil heat radiatin fins 8; similar fins 9,disposed transverse y to the line of the inlet and outlet passages 5 and6, are rovided on the outer surface of the top wail 10. Through the topwall 10, valve stem openin 11 are provided and communicate wit the inletand outlet passa es.

The mold in which the cylinder hea is cast comprises a bedplate 12 andtwo parts 13, separable on a lane normal to the fins on the top of thecy inder and containing the center lines of the inlet and outletpassages. The bedplate 12 has a flat surface 14 which is complemcntal tothe flat'surface 15 above the inlet passage 5 of the cylinder head, anda flat surface 16 which is complemental to the surface of the boss 16'around the exhaust valve stem opening. Upon these surfaces 15 and 16,the cast 0 linder head rests when the two parts of t e mold areseparated. At either end of the bedplate there is provided a recess orprint which receives complementary prints 17 on extended ends of thedisintegratable cores 18 and 19 which, with the valve stem cores 20 and21 extending through the bedplate, sup ort the cores 18 and 19. Thecores 18 and 19 are complementary in shape to the elbow inlet and outletpassages in the cylinder head. The separable parts of the mold havesurfaces complementary to that portion of the top of T the cylinder headwhic is between the flat surfaces 15 and 16 and at the right of the flatmine 16 as viewed in Figure 4, and also have surfaces com lementary tothe sides of the cg'linder hea As the two arts 13 are broug t togetherthey form, wit the bedplate, a mold about the inlet and outlet coreswhich mold is com lementary to the outer surface of the cylin er head.

The meeting faces of the mold parts 13 have three complementarysemicylindrical grooves outside the mold cavit two of the groovesextending laterally an bein alined and opposed to each other, and the tird being in the top at right angles to such line. The lateral groovesform cylindrical openings for the cores 22, and the grooves in f the toptogether form a cylindrical opening for the collapsible core which iscomplemen- {\ary:1 to the clearance cavity in the cylinder Thecollapsible core which forms the undcrcut clearance cavity in the bottomof the cylinder head comprises three parts, a central Eart 23, and twoside arts 24. Each of the t ree parts is rovide with a handle 25 bymeans of whic handles they may be inserted in the mold and withdrawnfrom the casting. The two side parts are rovided with projections 26which are complemental to the undercut recesses in the c linder head.The central part 23 has converging side faces which act as a wedgebetween the side parts 24. In placing the core in the mold the two sideparts 24 are inserted first, the amount which they will extend into themold being determined by lateral flanges 27 which engage the opening inthe mold and also the ends of the cores 18 and 19 with which thecontact. The central portion 23 is then placed between the two sideparts 24 and pushed into the mold until the lateral flan e 28 extendingtherefrom abuts a ainst tfie edge of the opening in the mold. e sparkplug cores are then entered through their openings to contact with theside parts 24 of the clearance cavity core.

The cores 22 extend to the base of the projections on the mold whichform the circumferential fins on the cylinder head. The aforementionedspark plug cores 29 extend in contact with the collaps1ble core forminthe clearance cavity in the cylinder head through an opening bored inthe res ective cores 22. The edges of the cores 22 orm a fiat surfaceadjacent the fins around the spark plug opening against which the flangeon the spark plug (not shown) abuts.

Into the mold or die assembled as hereinbefore described the metal ispoured, the parts of the mold being held together by the usual clampingmembers 30. After the metal has been poured the various permanent coresare removed and the dies are separated. he cast cylinder head is thenlifted from the bedplate 12 and the mold pre ared for another casting.The casting is subsequently heat treated which facilitates thedistintegration and removal of the cores in the elbow passages.

The molds are permanent, being made of steel, and produce accuratecastings which eliminate subsequent machining.

It is obvious that the order of the steps may be modified and thatvarious changes may be made in the illustrated embodiment of theapparatus used in carrying out my method within the principle and scopeof the appended claim.

I claim:

The method of forming a cylinder head or air cooled internal combustionengines which head is composed of an aluminum alloy and has a clearancecavity in its bottom, the sides of which are undercut in one transverseaxis and which has elbow inlet and exhaust passa es opening into the topof the cavity and Tateral spark lug openings into the cavity and a pluraity of ciryao cumferential cooling vanes and a plurality of parallel topcooling vanes disposed transverse to the said passages, which methodconsists in employing a permanent mold the parts of which are separableon a plane normal to the top vanes, inserting a three-part core axiallyin the mold cavity complemental in shape to the clearance cavity,inserting two lateral cores for the spark plu openings, supporting twodistintegratab e cores in the bottom of the mold complemental in shapeto the elbow passages pouring the metal into the mold cavity, thencollapsing and removing the three-part core and with-- drawing the coresfor the spark plug openings, opening the mold and removmg the casting,and disintegrating the cores in the elbow passages.

In witness whereof, I hereunto subscribe to my signature.

THEODORE PICKERING.

